Conventionally, the hydrogen separation membrane described in JAPANESE PATENT LAID-OPEN GAZETTE No. 7-185277 described below, for example, is known as a hydrogen separation membrane having a function to separate only hydrogen from a hydrogen-rich gas used in a fuel cell or the like. For the hydrogen separation membrane indicated in this literature, a hydrogen permeable metal layer (vanadium (V)) is used as the substrate, and both sides thereof are coated with a metal diffusion control layer. Also, the surfaces of such metal diffusion control layers are coated with palladium (Pd) as a catalytic metal in a membrane form, and the catalytic metal activates and promotes dissociation and bonding of hydrogen (hereinafter the catalytic metal is referred to as a hydrogen dissociation and bonding catalytic metal).
The palladium (Pd) used as the hydrogen dissociation and bonding catalytic metal in the hydrogen dissociation membrane described above is expensive, so there is a demand to control the quantity of palladium (Pd) used as much as possible.
The problem described above is not limited to only palladium (Pd), but also concerns other metals used in hydrogen dissociation and bonding catalytic metal.